Prefabricated chimney



Dec. 8, 1964 J. H. c. DAVIDSON PREFABRICATED CHIMNEY 2 Sheets-Sheet 1 Filed May 11, 1962 INVENTOR JOHN H. c. DAVIDSON WWW ATTORNEYS Dec. 8, 1964 .1. H. c. DAVIDSON PREFABRICATED CHIMNEY 2 Sheets$heet 2 Filed May 11, 1962 QMM FIG. 2

INVENTOR JOH N H. C. DAVIDSON imzw United States Patent 3,169,087 PREFAERICATED CHEMNEY John E C. Davidson, fit. George, @ntarie, Canada, as-

signor to Selkirk Metal Products (1964) Ltd, Ontario, Canada Filed May 11, 1962, tier. No. 194,tl9 2 Claims. (ill. 98-46) This invention relates to a chimney of the type that is prefabricated in sections for assembling in an operative position in a building.

Prefabricated chimney constructions of the general type with which this invention is concerned are in common use. They, by customary standard, include an external casing, an interliner, a fire tube, and a starter box adapted to support the casing, fire tube and interliner in; spaced relation in a building structure. Means which are adapted to space the interliner between the casing and the fire tube to define an air pathof annular cross-section that extends downwardly between the casing and the interliner and upwardly between the interliner and the tire tube are provided.

It has been the practice, with chimney constructions of this general type, to support all three, the casing, the fire tube and the interliner from the starter box with the result that it has been difficult and, in many cases, impossible to remove the fire tube without removing the entire chimney. This is a limitation of the effectiveness of the chimney be cause, in use, the fire tube does tend to deteriorate before the other elements, and often requires early replacement. In addition, the starter box in the earlier construction is open to, and, therefore, vulnerable as a result of moisture that enters from the outside.

It has also been the practice with constructions of this general type to provide a rain cap that overlies the fire tube to prevent undue rain and snow from entering the fire tube.

It is an object of this invention to provide a chimney construction of the general type referred to that is supported by support means that engages with the external casing.

It is a further object of the invention to provide a chimney construction of the type referred to wherein the fire tube is supported by support means carried by the external casing whereby the fire tube can be removed from either the top or the bottom without removing the entire chimney assembly from the building.

It is a further object of the invention to provide a chimney construction wherein the mounting means is not affected by moisture conditions in the chimney that enter from outside the building.

It is a further object of the invention to provide a chimney construction wherein the fire tube is supported by the external casing and a spacer is provided that permits ready removal of the fire tube without removing the chimney mounting in a building construction.

t is a further object of the invention to provide a chimney construction having a venturi section at the mouth of the air flow path between the interliner and the fire tube to induce the air flow through the path whereby the size of the chimney can be reduced to a point where a necessity for a rain cap is lessened.

A chimney according to this invention comprises an external casing, a fire tube, and an interliner. First support means engage with the casing to mount the chimney in an operative position, second support means are carried by the casing to support the fire tube, and third support means to support the interliner in the casing in customary spaced relation to the casing and fire tube. Spacing means are provided for maintaining the casing fire tube and interliner in customary spaced relation, and the second support means is releasable so that the fire tube can be removed from the chimney construction.

Patented Dec. 8, i964 ice The invention also contemplates the use of a skirt at the upper extremity of the construction that combines with the upper extremity of the path between the fire tube and the interliner to make a venturi section to induce air flow from the air path between the interliner and the fire tube whereby to increase the cooling efiiciency of the air path and permit the construction of a chimney to generally smaller proportions. The invention will be understood following a reading of the detailed specification, read in conjunction with the drawings.

In the drawings:

FIGURE 1 is a view of an assembled chimney, broken away and showing the manner in which it is mounted in the building;

FIGURE 2 is a view along the line 2-2 of FIGURE 1 showing the spacing means of the chimney elements; and

FIGURE 3 is a detailed section showing the support means.

The numeral 10 generally refers to a chimney which comprises an external casing 12 having a tubular sheet metal wall, a fire tube 14 having a tubular sheet metal wall, and an interliner 16 having a tubular sheet metal wall.

The external casing, fire tube and interliner are constructed in sections that fit together according to standard practice.

The chimney is supported in the building between adjacent joists 18 by means of support plates 29 that are nailed to the joists and stapled to the flanged ends 22 of the channel shaped support member 24. Channel shaped support member 24 has a circular hole 25 in its bottom to admit a cross-section of the external casing'lZ so that the head of the external casing rests on the marginal edge of the opening to support the chimney in use.

The channel support 24 has flanges 23 on two side walls. Strips 27, having an L cross-section, are stapled to the end plates 24) to form with the flanges 23 a continuous flange rim that extends around the mounting assembly.

The flange rim serves to strengthen and locate the mounting member under the joists.

The interliner 16 is supported by the brackets 40 that are stapled to the inside of the external casing by means of a flange (not shown) that abuts the external casing.

The fire tube :14 is supported by means of plate that is bolted as at 51 to the bottom of the external casing and that has a round hole 52 therein, the marginal edges of which engage with a bead of the fire tube to support the fire tube in position.

The three sections are maintained in spaced apart relation by means of a plurality of bars 6t), each extending through the wall of the interliner to form a chord of a diameter thereof and combining with two others to restrain the fire tube within the interliner. Considerable play is possible so that, by releasing the plate 545 that holds the fire tube, the fire tube can be dropped from the bottom without disturbing the fire tube or the casing. This is important for replacement of the fire tube.

This chimney is also unique at its upper end. At the upper end, it comprises a skirt having a fustroconical section 69, a downwardly depending outer part 62, and a downwardly depending inner skirt 64. Skirt 64 has an external bead 66 adjacent its lower edge and, in use, telescopes into the upper end of the interliner 16 to support the cap in an operative position on the assembly.

The downwardly depending part 62 of the skirt is in spaced relation to the external casing 12 and defines therewith a portion of an air flow path that has an annular crosssection. The complete air path will be referred to again later. Spacing lugs 68 are carried by the downwardly depending part of the skirt to space it evenly from the external casing.

.path between the'fire tube 14 and the "interliner 16 at 'the top thereof to concentrate 'thedischarge of gases'from the gas tube in use and create high velocity.

In use, a continuous air path of annular cross-section extends upwardly between the skirt 62 'and'the outer surface of .the exterior casing 12,'downwardly between'the exterior casing 12 and-thejnterliner 16, around'the'bottom of the interliner, upwardly'rbetween the vinterliner 16 and fire tube 14 and out the venturhsection'defined by the skirt and upper portionof the fire tube 70. Air

travelling this path cools the-chimney and the chimney must be designed to provide for the required amount of cooling air underoperating conditions. "By increasing the rate-of flow through this path with aventuri section at the upper end,'the dimensions of 'thepath can be reduced to achieve a given rate of air flow. Thus, with the venturi section as provided; it is possible to manufacture a chimney having a given capacity-with smaller vdimensions. It has been found that a frustro-conical restriction at theupper end-of thefire tube, While not materially restricting the flow of hot gases through the fire .tube, increases the velocity at the outlet of thefire tube, thereby producing a venturi or nozzle etfect that tends to excite the release of air from between the interliner and gas tube. Thus, the -frustro-conical section has achieved an improved flow of cooling air-withoutrestricting the capacity of the chimney'to handle hot gases from'the furnace.

The manner of using the chimney will be apparent to those skilled in the art. The chimney is built up in any length desired by using an appropriate number of sections, as is well known in the art. The discharge from the furnace is fed into lower end of the fire tube 14 in the usual way. Cooling takes place as air travels the cooling path above described.

What I claim as my invention is:

1. A chimney comprising an external casing having a tubular Wall, a fire tube having a tubular Wall of smaller diameter than said external casing, an interliner having a tubular wall of a diameter greater than said fire tube and smaller than said tubular wall of said external casing, first support means adapted to grip said external casing and connect with a mounting structure to mount said chimney in an operative position in use, second support means adapted to be carried by said external'casing for releasably supporting said fire tube from falling due to gravity within said external casing,.third support means for supporting said interliner in-said casing in spaced relation to said external casing and said fire tube, and spacing means for maintaining the external casing, fire tube and interliner in spaced relation with their tubular walls in substantially concentricspaced relation to form air paths whensaid chimney is in an operative position.

2. A chimney as claimed in claim 1 in which said second support means comprises bracket means releasably securable to said external casing and adapted to engage with and support said fire tube adjacent a free end.

References Cited by the Examiner UNITED STATES PATENTS 995,097 6/1 1 Schofer 9846 2,634,720 4/ 53 Thulman 9845 2,648,511 8/53 Epstein 9846 2,695,554 11/54 Jensen 9846 3,087,408 4/63 Carr 9846 ROBERT A. OLEARY, Primary Examiner.

EDWARD 5. MICHAEL, Examiner. 

1. A CHIMNEY COMPRISING AN EXTERNAL CASING HAVING A TUBULAR WALL, A FIRE TUBE HAVING A TUBULAR WALL OF SMALLER DIAMETER THAN SAID EXTERNAL CASING, AN INTERLINER HAVING A TUBULAR WALL OF A DIAMETER GREATER THAN SAID FIRE TUBE AND SMALLER THAN SAID TUBULAR WALL OF SAID EXTERNAL CASING, FIRST SUPPORT MEANS ADAPTED TO GRIP SAID EXTERNAL CASING AND CONNECT WITH A MOUNTING STRUCTURE TO MOUNT SAID CHIMNEY IN AN OPERATIVE POSITION IN USE, SECOND SUPPORT MEANS ADAPTED TO BE CARRIED BY SAID EXTERNAL CASING FOR RELEASABLY SUPPORTING SAID FIRE TUBE FROM FALLING DUE TO GRAVITY WITHIN SAID EXTERNAL CASING, THIRD SUPPORT MEANS FOR SUPPORTING SAID INTERLINER IN SAID CASING IN SPACED RELATION TO SAID EXTERNAL CASING AND SAID FIRE TUBE, AND SPACING MEANS FOR MAINTAINING THE EXTERNAL CASING, FIRE TUBE AND INTERLINER IN SPACED RELATION WITH THEIR TUBULAR WALLS IN SUBSTANTIALLY CONCENTRIC SPACED RELATION TO FORM AIR PATHS WHEN SAID CHIMNEY IS IN AN OPERATIVE POSITION. 